#include<stdio.h>

long fib(int n);
int main(int argc, char *argv)
{
	int n;
	long ans;
	
	scanf("%d", &n);
	ans = fib(n);

	printf("斐波那契数列的第%d项为%ld\n", n, ans);

	return 0;
}


long fib(int n){
	if(n < 0)
		return -1;
	else if(1 == n || 2==n)
		return 1;
	else 
		return fib(n - 1) + fib(n - 2);
}

